Pump, in particular for a hydraulic unit

ABSTRACT

The invention improves a pump provided with an eccentric cam bearing, a drive bearing, a drive shaft, an electric drive motor, and a pump housing. According to the invention, the pump housing includes a compensating chamber that enlarges a cam chamber of the cam bearing, to advantageously interrupt a transmission path for a leakage fluid from the cam chamber into the electric drive motor of the pump

PRIOR ART

The invention relates to a pump, in particular for a hydraulic unit, according to the preamble of the independent claim 1.

A conventional pump, in particular for a hydraulic unit, is depicted in FIG. 1. As is clear from FIG. 1, the conventional pump 1 includes a cam bearing 2, a drive bearing 3, a drive shaft 4, an electric drive motor 5, a pump housing 6 equipped with a motor bore 6.1, and a drive shaft bearing 7. When the pump 1 is embodied as part of an ABS system and/or an ESP system, during operation of the pump, a capillary action due to the narrow gaps in a cam chamber 2.1 can cause small quantities of brake fluid to seep from the pump elements and penetrate directly into the cam bearing 2. The brake fluid that gets into the cam bearing 2 can be transported further into the electric drive motor 5 via the drive bearing 3. This leakage path of the brake fluid is indicated by the arrow 8 in FIG. 1. In addition, the above-mentioned capillary action prevents the brake fluid from draining into optionally provided leakage pockets.

A penetration of brake fluid into the electric drive motor 5 can lead to increased current values and reduced brush wear. In the extreme instance, the brake fluid penetrating into the electric drive motor 5 can cause a short-circuit and therefore a failure of the electric drive motor 5. A penetration of brake fluid into the cam bearing 2 and/or the drive bearing 3 can cause a leaching out of the grease and therefore to increased wear.

DISCLOSURE OF THE INVENTION

The pump according to the invention, with the defining characteristics of the independent claim 1, has the advantage over the prior art that a cam chamber of a cam bearing is enlarged by compensating means that are let into a pump housing. The compensating means prevent or hinder a capillary action between the cam chamber and the cam bearing, i.e. the compensating means according to the invention advantageously interrupt a transmission path for a leakage fluid from the cam chamber into an electric drive motor of the pump. The compensating means advantageously avoid the presence of narrow gaps in the cam chamber, making it possible to reduce the danger of capillary action and making it possible to almost completely prevent a penetration of fluid from the cam chamber into the cam bearing.

Advantageous improvements of the pump disclosed in the independent claim are possible by means of the measures and modifications disclosed in the dependent claims.

It is particularly advantageous that the compensation means are embodied in the form of an annular groove that can easily be let into the pump housing. The compensating means embodied in the form of an annular groove require no additional space so that no further changes are required in the pump housing, for example with regard to the placement of a drive shaft bearing, which prevents a general deepening of the motor bore in order to enlarge the cam chamber. The cross section of the annular groove can, for example, be square or round.

In one embodiment of the pump according to the invention, the compensation means achieve an interruption of a leakage path of a leakage fluid between the cam chamber and the electric drive motor and achieve a drainage of the leakage fluid into a leakage reservoir.

In another embodiment of the pump according to the invention, the leakage reservoir can, for example, be situated at the bottom of a motor bore in the pump housing.

The pump according to the invention can, for example, be used in a hydraulic unit of an ABS (antilock brake) system and/or an ESP (electronic stability program) system.

The drawings show advantageous embodiments of the invention described below and the conventional exemplary embodiment explained above for better comprehension of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a longitudinal section through a detail of a conventional pump for a hydraulic unit.

FIG. 2 shows a longitudinal section through a detail of a pump according to the invention, which is intended for a hydraulic unit.

FIG. 3 shows a cross section through the pump according to the invention along the line A-A from FIG. 2.

EMBODIMENT(S) OF THE INVENTION

As shown in FIGS. 2 and 3, in a fashion analogous to the conventional pump 1 shown in FIG. 1, a pump 1′ according to the invention has a cam bearing 2, a drive bearing 3, a drive shaft 4, an electric drive motor 5, and a pump housing 6′. As is also clear from FIG. 2, the pump housing 6′ has an annular groove 9 serving as a compensation means let into it, which enlarges a cam chamber 2.1 of the cam bearing 2.

In the exemplary embodiment shown, the annular groove 9 has a square cross section. In an alternative embodiment that is not shown, the annular groove 9 can have a round cross section.

The compensating means 9 according to the invention advantageously avoid the presence of narrow gaps in the cam chamber 2.1 of the cam bearing 2, thus preventing a capillary action from being exerted on a leakage fluid that is generated and interrupting the leakage path 8—shown in FIG. 1—of the leakage fluid between the cam chamber 2.1 and the electric drive motor 5. Instead, the compensation means 9 cause the leakage fluid to drain into a leakage reservoir 10, which in the exemplary embodiment shown, is situated at the bottom of a motor bore 6.1 in the pump housing 6.

The drainage of the leakage fluid is indicated by a black arrow in FIG. 3. Consequently in the pump 1′ according to the invention, the leakage fluid does not travel into the cam bearing 2 and from there via the drive bearing 3 into the electric drive motor 5, but instead travels downward in the motor bore 6.1 and can be conveyed away into the leakage reservoir 10.

In the pump 1′ according to the invention, a leakage fluid, e.g. brake fluid, that emerges from the pump elements is prevented from entering into the cam bearing 2 and then being transported onward into the electric drive motor 5. This significantly increases the system's resistance to the entry of brake fluid and thus also significantly extends the service life of the electric drive motor 5, the cam bearing 2 and the drive bearing 3.

The pump according to the invention can be used, for example, in a hydraulic unit of an ABS system and/or an ESP system. 

1-6. (canceled)
 7. A pump comprising: a cam bearing disposed in a cam chamber, a drive bearing, a drive shaft supported by the drive bearing, an electric drive motor driving the drive shaft, a pump housing, and compensating means disposed in the pump housing which enlarge the cam chamber of the cam bearing.
 8. The pump as recited in claim 7, wherein the compensating means are embodied in the form of an annular groove.
 9. The pump as recited in claim 8, wherein the annular groove has a square or round cross section.
 10. The pump as recited in claim 7, wherein the compensating means interrupt a leakage path of a leakage fluid between the cam chamber and the electric drive motor and drain the leakage fluid into a leakage reservoir.
 11. The pump as recited in claim 8, wherein the compensating means interrupt a leakage path of a leakage fluid between the cam chamber and the electric drive motor and drain the leakage fluid into a leakage reservoir.
 12. The pump as recited in claim 9, wherein the compensating means interrupt a leakage path of a leakage fluid between the cam chamber and the electric drive motor and drain the leakage fluid into a leakage reservoir.
 13. The pump as recited in claim 10, wherein the leakage reservoir is situated at the bottom of a motor bore disposed in the pump housing.
 14. The pump as recited in claim 11, wherein the leakage reservoir is situated at the bottom of a motor bore disposed in the pump housing.
 15. The pump as recited in claim 12, wherein the leakage reservoir is situated at the bottom of a motor bore disposed in the pump housing.
 16. The pump as recited in claim 7, wherein the pump is used in a hydraulic unit of an ABS system and/or an ESP system.
 17. The pump as recited in claim 8, wherein the pump is used in a hydraulic unit of an ABS system and/or an ESP system.
 18. The pump as recited in claim 9, wherein the pump is used in a hydraulic unit of an ABS system and/or an ESP system.
 19. The pump as recited in claim 10, wherein the pump is used in a hydraulic unit of an ABS system and/or an ESP system.
 20. The pump as recited in claim 11, wherein the pump is used in a hydraulic unit of an ABS system and/or an ESP system.
 21. The pump as recited in claim 12, wherein the pump is used in a hydraulic unit of an ABS system and/or an ESP system.
 22. The pump as recited in claim 13, wherein the pump is used in a hydraulic unit of an ABS system and/or an ESP system.
 23. The pump as recited in claim 14, wherein the pump is used in a hydraulic unit of an ABS system and/or an ESP system.
 24. The pump as recited in claim 15, wherein the pump is used in a hydraulic unit of an ABS system and/or an ESP system. 